A material to coat a bottom of a ship that is now widely employed is an antifouling coating material containing a component such as a (meth)acrylic acid metal salt copolymer and a silyl ester copolymer, and various antifouling agents, for its ability to exhibit good consumption property and good antifouling property. However, in less often ship-operating, or under certain sea conditions, animals, e.g., barnacles, and slimes (microorganism coating), e.g., diatoms, adhere onto the substrate of the ship, often causing a problem.
In view of the above, conventional antifouling coating composition contained a copper compound, e.g., cuprous oxide, aimed at preventing the adhering of the barnacles and the like, or an organic antifouling agent intended as an anti-slime agent, e.g., N,N-dimethyl-N′-phenyl-(N-fluorodichloromethylthio)sulfamide, 2,4,6-trichlorophenylmaleimide, and 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine.
These conventional antifouling coating compositions, however, need to contain an antifouling agent in a large amount in order to sufficiently exhibit an antifouling effect, and this has an adverse effect on coating film property.
For this reason, there has been a demand for an antifouling coating composition excellent in coating film property which has stable coating film consumption degree on ships, underwater structures and the like and which exhibits excellent antifouling property over a long term.
Patent document 1 describes the use as an antifouling component of medetomidine bonded to metal nanoparticles. Patent document 2 describes the use as an antifouling component of medetomidine bonded to a skeleton of a polymer such as polystyrene and an acrylate polymer. Patent document 3 describes a protective coating containing medetomidine and an organic antifouling agent such as 3-(3,4-dichlorophenyl)-1,1-dimethyl urea serving as an algal inhibitory substance. Patent document 4 describes the use of medetomidine as a chemical to inhibit marine biofouling, and further describes the blending of medetomidine into a coating material containing an acrylic polymer.
Still, it is difficult for these conventional antifouling coating compositions to form an antifouling coating film which has stable coating film consumption degree on ships, underwater structures and the like and which exhibits excellent antifouling property over a long term.